Two Co. Tyrone farmers have been hospitalised, and three animals have died, in a slurry accident just hours before this year's closed period began.
The men were overcome with fumes as they worked to put out slurry on Saturday, October 14.
It is understood their injuries are not life-threatening. However, three animals in the vicinity at the time were killed in the incident.
Police, and other emergency services, were called to the farm in the Fintona area.
The men were treated at the scene and later transferred to hospital in Enniskillen.
PSNI inspector Latimer said: “It is believed at this stage that the men were mixing slurry at the time of the accident. However, the Health and Safety Executive has been notified and further enquiries into the incident will be carried out in due course.
"This was a serious incident which could have ended very differently; and maybe it is a timely reminder for all those involved in mixing slurry to examine their working practices.”
The slurry ban was first introduced in Northern Ireland in 2007, and has been widely criticised by farmers ever since.
It comes just days after the Ulster Farmers Union (UFU) advised farmers who could not empty their tanks in time, to use the "last resort" of the 'reasonable excuse' clause in the Nitrates Action Programme.
The UFU advised farmers to take extra care when mixing and warned that the wet weather had made it “nearly impossible” to spread slurry safely.
The clause would allow farmers to continue spreading a limited amount under extreme circumstances, without notifying the department or the Northern Ireland Environment Agency (NIEA).
Just last year, Co. Tyrone dairy farmer Alistair Sloss was killed in a slurry accident one day before the closed period was set to begin.
Alistair was overcome by fumes while mixing, and fell into a slurry tank at his farm in Coagh.
Five cows were also killed in the same incident.